Production of acetylene



NOV. 24, 1970 BARTHOLOME ETAL 3,542,894

. PRODUCTION OF ACETYLENE Filed March 22, 1968 z Sheets-Sheet 1 FIG. 2

PRIOR ART u. INVENTORS:

Q ERNST BARTHOLOME HANS FRIZ FRANZ NEU R MARTIN REI RT FIG. I

PRIOR ART ULRICH WAGNER ATT'YS Nov. 24, 1970' E. BARTHOLOME ETAL 3,542,894

PRODUCTION OF ACETYLENE Filed March 22, 1968 i z Sheets-Sheet 2 v o 4 c: mvemohs:

ERNST BARTHOLOME RIZ FIG. 3'

. HANS F FRANZ NEUMAYR TIN REIC T. RICH WAG ATT'YS United States Patent 3,542,894 PRODUCTION OF ACETYLENE Ernst Bartholome, Heidelberg, Hans Friz and Franz Neumayr, Ludwigshafen (Rhine), Martin Reichert, Frankenthal, Pfalz, and Ulrich Wagner, Limburgerhof, Pfalz, Germany, assignors to Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen (Rhine), Germany Filed Mar. 22, 1968, Ser. No. 715,369 Claims priority, application Germany, Mar. 25, 1967, 1,618,125 Int. Cl. C07c 11/24 US. Cl. 260-679 Claims ABSTRACT OF THE DISCLOSURE A process for the production of acetylene by partial oxidation of hydrocarbons with oxygen, the flame formed in the oxidation being stabilized by auxiliary oxygen which is injected into the gas mixture at an angle of from more than 0 to 90 to the direction of flow of the gas mixture. The acetylene yield is thus improved and the amount of soot formed is decreased.

The present invention relates to a process for the production of acetylene by partial oxidation of hydrocarbons with oxygen with the formation of a flame, this flame being stabilized by auxiliary oxygen which is injected into the gas mixture at an angle to the direction of flow thereof of from more than 0 to 90.

In the production of acetylene by partial oxidation of hydrocarbons (for example C to C hydrocarbon) with oxygen by prior art methods, the two components are heated separately to about 250 to 700 C. and then mixed with each other in a mixing unit. The mixture then flows through a burner block and is thereafter caused to react in the combustion chamber. This reaction is a flame re action which takes place within ,4 to A of a second at a temperature of about 1200 to 1600" C. of a flame. After the formation of acetylene has ended the temperature is lowered to about 50-300 C. as rapidly as possible (within about to 7 of a second) by injecting a liquid (water or hydrocarbons, in particular fairly highboiling heat-resistant hydrocarbons such as naphthalene or substituted nahpthalenes) into the current of gas in order to prevent decomposition of the acetylene formed.

FIGS. 1 and 2 of the drawing, which are respectively a section of a prior art acetylene burner and a plan view of the burner block as seen from the combustion chamber, show the characteristic features of a prior art acetylene burner such as is used in industrial plant. The reaction mixture of hydrocarbon and oxygen, which has been preheated flows through a diffuser A to the burner block B, which contains a number of parallel, preferably cylindrical channels C through which the gas mixture flows at a velocity which is greater than the velocity of the flame.

The gas mixture, which contains 20 to 80% by volume of hydrocarbons and 80 to 20% by volume of oxygen, flows into a combustion chamber H which is bounded by the burner block B and a water-cooled jacket K. Oxygen is injected at the front face of the burner block (at E, hereinafter called auxiliary outlet) through line D. It enters the combustion chamber H parallel to the direction of flow of the mixture. In addition, oxygen is supplied through lines F in the jacket K perpendicular to the direc tion of flow on the mixture (at G, hereinafter called jacket outlets). When the burner is started up, hydrocarbon is at first supplied by itself through the diffuser to the burner block B, through the channels C into the combustion chamber H.

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The oxygen passed through D and F (hereinafter called auxiliary oxygen) is ignited in this combustible gas and burns at auxiliary outlets E and jacket outlets G, forming small flames. After the auxiliary oxygen has been ignited, the amount of oxygen required for the reaction is mixed with the hydrocarbon, the auxiliary oxygen flames igniting the mixture in the reaction chamber and stabilizing the reaction flame during continuous operation. During continuous operation the ratio of the oxygen issuing from the auxiliary outlets to the oxygen contained in the gas mixture issuing from the channels is in general from 1:1000 to 1:10.

It has become evident that this type of stabilization of the reaction flame has disadvantages, particularly in the case of flames formed by partial oxidation of vaporized liquid hydrocarbons, for example those having 5 to 10 carbon atoms. The flame is stabilized at very diflerent distances from the burner block. Flames of this type are unfavorable because they result in differences in residence times of the hot acetylene in the combustion chamber and consequently in diminished production of acetylene and increased formation of soot.

It is an object of this invention to provide a process for the production of acetylene in such a way that the content of acetylene in the reacted gas is increased.

Another object if the invention is to decrease the soot content in the gas obtained.

These and other objects of the invention are achieved by directing the auxiliary oxygen issuing from the burner block so that it forms an angle of considerably more than 0, for example 20, and not more than 90, preferably from 60 to with the direction of the gases issuing from the burner block. Thus the auxiliary oxygen is supplied through the auxiliary outlets not parallel to the stream of the reaction mixture, but at an angle at E, as shown in FIG. 3. The angle a at which the auxiliary oxygen impinges on the reaction mixture may be varied within wide limits of from more than 0 to not more than preferably from 20 to 90 and particularly from 60 to 80", without the stabilization of the reaction flame being impaired.

It is advantageous for one or more auxiliary oxygen flames to be pointed toward each channel in the burner block. It has been found to be expedient to arrange the auxiliary outlets between the channels in such a Way that three flames issue from each auxiliary outlet into the combustion chamber and either one, two or three auxiliary flames are pointed toward each channel. FIG. 4 of the accompanying drawing shows one of these arrangements in which the auxiliary outlets and the channels form a hexagonal pattern in the cross-section of the burner block and in which three auxiliary flames are pointed toward one flame issuing from the channels except some of those channels situated next to the jacket and toward which only two auxiliary flames are pointed.

The result of the process according to the invention is that a gas is obtained having both a higher acetylene content and a lower soot content than has been possible in the prior art methods using the same hydrocarbon mixture.

It has also been found that a prior art burner block can be subjected to much greater loads in the process according to this invention than in the prior art methods.

The process according to this invention is illustrated by the following example.

EXAMPLE 530 kg. of naphtha (specific gravity 0.69, boiling point range 34 to 124 C., vapor density 4.0 kg./m. at STP.) per hour is vaporized in a preheater and heated to 320 C. The naphtha vapor is mixed in a mixing unit with 380 m.

(STP.) of oxygen which has also been heated to 320 C. in a separate preheater, and then passed through the diffuser of an apparatus according to the invention to the burner block. Prior to entering the burner block, the mixture has a temperature of 280 C. The water-cooled burner block (FIG. 4) contains nineteen channels C each having a diameter of 19 mm. They are arranged in a. hexagonal pattern whose parallel outer boundary lines K are spaced apart by a distance of 165 mm.

The mixture is ignited in the reaction chamber H (FIG. 3) which is bounded by the burner and the water-cooled combustion chamber K having a length of 250 mm. The auxiliary oxygen (4 m. per hour at STP.) is supplied through line D and auxiliary outlets E to the reaction mixture at an angle oc=60. Another 4 in. per hour (STP.) of oxygen is introduced through line F and auxiliary outlets G. After reaction has taken place, the mixture is quenched to 80 C. by injecting water.

1156 m. per hour at STP. of dry cracked gas is obtained having the following composition:

Percent by volume and 13 g./m. (STP.) of soot.

From this it can be calculated that the yield is 134 kg./h. of C H with a specific naphtha consumption of 3.95 kg. per kg. of C H a specific oxygen consumption of 4.07 kg. per kg. of C H and a specific oxygen consumption of 4.07 kg. per kg. of C H and a specific soot formation of 0.11 kg. per kg. of CgHg.

For comparison, the same reaction is carried out in a prior art burner block having identical dimensions to those of the above block. In this case, however, the auxiliary oxygen is introduced into the reaction chamber H at E parallel to the stream of reaction mixture (::0) as shown in FIG. 1. In this arrangement, 400 kg. of naphtha of the abovementioned type and 268 m. (STP.) of oxygen are reacted per hour; at a higher load, the reaction flame becomes unstable and some unreacted oxygen is found in the quenched acetylene-containing gas. 6 m. (STP.) per hour of auxiliary oxygen is supplied at each of the outlets E and G. The other operating data are the same as described above.

When using this method, 870 m. (STP.) per hour of dry cracked gas is obtained having the following composition:

Percent by volume and 19.4 g./m. (STP.) of soot. From this it can be cal- 4 culated that the yield of C H is 82.5 kg. per hour of acetylene with a specific naphtha consumption of 4.04 kg. per kg. of C H a specific oxygen consumption of 4.10 kg. per kg. of C H and a specific soot formation of 0.17 kg. per kg. of C H We claim:

1. A process for the production of acetylene by partial oxidation of hydrocarbons with oxygen wherein the gaseous or vaporous components are separately preheated and then mixed, the mixture is passed through channels in a burner block to a combustion chamber and the flame in said combustion chamber as stabilized by auxiliary flames which are fed with auxiliary oxygen which issues from said burner block at an angle of 20 to 90 to the direction of said mixture issuing from said burner block.

2. In a process for the production of acetylene by partial oxidation of gaseous or vaporous hydrocarbons with oxygen wherein the gaseous or vaporous components are separately preheated to a temperature ranging from 250 to 700 C. and then mixed, the mixture containing 20 to 80% by volume of hydrocarbons and 80 to 20% by volume of oxygen is passed through a plurality of parallel channels in a burner block to a combustion chamber where the partial oxidation takes place at a temperature ranging from 1200 to 1600 C., the gas mixture then being quenched rapidly by injection of water or hydrocarbon to temperatures of from 50 to 300 C., and wherein the flame in said combustion chamber is stabilized with auxiliary flames by feeding auxiliary oxygen through auxiliary outlet-s, the molar ratio of said auxiliary oxygen to the oxygen contained in said gas mixture being 1:1000 to 1:10, the improvement which comprises providing means at said auxiliary outlets which cause the auxiliary oxygen to issue at an angle of 20 to 90 to the direction of said mixture issuing from said channels of said burner block.

3. A process as claimed in claim 1 wherein one or more than one auxiliary oxygen flame is provided for each channel in the burner block.

4. A process as claimed in claim 2 wherein the angle between the emerging auxiliary oxygen and the emerging mixture is from to 5. A process as claimed in claim 1 wherein the angle between the emerging auxiliary oxygen and the emerging mixture is from 60 to 80.

References Cited UNITED STATES PATENTS 3,438,741 4/1969 Boyd et al 23277 3,121,616 2/1964 Braconier et a1. 23277 2,998,464 8/1961 Burleson et al. 260679 DELBERT E. GANTZ, Primary Examiner I. M. NELSON, Assistant Examiner US. Cl. X.R. 23-277; 260683 

